At this time of year a lot of snakes will stop eating due to sensing the change in season, you can try to counter this by increasing their temps and daylight hours or brumate them, one or the other should stimulate them to eat.

How old the snake is and how much fat reserves it has will determine how long it can go without eating, I had a well fed 8 month old infernalis go 6 months without eating(4 months pre brumation, decided to brumate to stimulate appetite).